Search Results (2,794)

For hydrogen refueling stations, metal hydride compressors offer a safe and efficient alternative to mechanical systems. This work systematically investigates Ti_0.94Zr_0.08Cr_1.0Mn_0.6−xFe_0.4+x (x = 0, 0.1, 0.2, 0.3, 0.4) alloys for primary hydrogen compression targeting 25 MPa. All alloys crystallize as a single C14 Laves phase, with Fe substitution causing negligible lattice changes but leading to linearly increased particle size due to solid-solution strengthening. In the testing temperature range of −80 to −50 °C, the hydrogen storage capacity decreases with increasing Fe, whereas the effective desorption capacity improves. Pressure–composition isotherms exhibit single plateaus with elevated plateau pressures at higher Fe/Mn ratios. In the range of x = 0–0.4, the enthalpy of desorption decreases in magnitude with Fe content. Using Van’t Hoff extrapolations to 30 °C absorption and 80 °C desorption, the compression factor shows a non-monotonic trend, reaching a maximum of 1.99 at x = 0.2. This composition provides nearly a two-fold pressure boost, demonstrating promise for low-grade heat driven hydrogen compression in refueling infrastructure. Full article

Dissolved oxygen concentration is a key parameter determining the oxidation and corrosion behavior of structural materials in lead-based fast reactor coolants. Therefore, achieving high-precision in-situ oxygen measurement in LBE systems is a fundamental technical requirement for implementing oxygen-controlled corrosion protection. Currently, nuclear-grade Bi/Bi₂O₃ solid-state electrochemical oxygen sensors have a minimum effective operating temperature of 350 °C, which prevents them from meeting the real-time oxygen monitoring needs under low-temperature conditions. This temperature limitation has become a major bottleneck for the engineering application of oxygen control technology. To address these requirements and challenges, this study develops a novel electrochemical oxygen sensor based on an 8 mol% Y₂O₃-stabilized ZrO₂ (8YSZ) solid electrolyte and La_0.6Sr_0.4Co_0.2Fe_0.8O_3±δ (LSCF) electrode system. Comparative experiments with Bi/Bi₂O₃ sensors are conducted to quantitatively assess the advantages of the LSCF/Air sensor in low-temperature applications within 205~550 °C. Furthermore, considering the irradiation environment in nuclear reactors, oxygen ion irradiation was employed as an accelerated simulation method to preliminarily investigate the electrochemical transport properties of 8YSZ after irradiation. The effects of oxygen ion irradiation on the apparent impedance and apparent oxygen ion conductivity of 8YSZ were evaluated. The results show that the LSCF/Air oxygen sensor has the potential to extend the lower operating-temperature limit of 8YSZ-based oxygen sensors in static, oxygen-saturated LBE environments. Oxygen ion irradiation increased the apparent impedance and decreased the apparent ionic conductivity of the tested 8YSZ samples. These results provide preliminary experimental data for the development of oxygen sensors for oxygen monitoring and corrosion control in liquid-metal-cooled reactor systems over a wider temperature range. Full article

This study employs molecular dynamics (MD) simulations to explore the high-speed impact behavior of double conical tungsten (W) fragments on titanium (Ti) target plates, focusing on fragment cloud formation, Ti damage evolution, and the effects of temperature and impact velocity. High-speed impact converts W fragments’ kinetic energy into internal energy, causing W fragmentation and the formation of a mixed-phase fragment cloud, which induces severe damage to the Ti target. Under double-particle impacts, W fragments penetrate the Ti target to form a multi-source fragment cloud, with Ti target damage (characterized by amorphous phase distribution) undergoing initiation and extension stages. Higher temperatures broaden the high-temperature damage zone and increase crater size but do not change the impact penetration evolution mode or penetration depth. Impact velocity determines damage modes: low velocity causes non-through internal damage with a rear bulge, while high velocity leads to full perforation with mixed W-Ti fragment ejection, and lateral crater size is almost unaffected by velocity. This study innovatively reveals the atomic-scale damage evolution mechanism of Ti targets under dual conical W fragment impact, which fills the research gap in conventional single-fragment impact studies. These findings clarify the high-speed impact mechanism of Ti alloys, providing theoretical support for the design of Ti-based protective structures in engineering. Full article

Deposit return systems (DRS) can increase the capture of beverage packaging, but material circularity is not determined by return rate alone. A returned container contributes to high-value circularity only if it passes recognition, sorting, pre-processing, and material-specific quality gates. This article evaluates the material-quality performance of three returned beverage-packaging materials—polyethylene terephthalate (PET), aluminium and reusable glass—using a quality-gated high-value recovery framework. The model defines a high-quality recovery index, HQR = R × Q × Y, where R is the return rate, Q is the quality factor of the returned stream, and Y is the reprocessing or reuse yield. The HQR indicator describes the quality of the entire DRS process. The core purpose of the HQR model is to distinguish nominal packaging return from high-quality material recovery and to show whether returned PET, aluminium and reusable glass streams remain suitable for high-value circular pathways. A survey-supported early-stage return scenario (R = 0.50) is compared with the 77% and 90% separate-collection targets used in European policy. To strengthen the PET branch of the model, a pilot PET stream-quality and processing-yield dataset was incorporated, including PET purity, colour composition, non-PET impurities, residual moisture, organic residues, intrinsic viscosity, washed PET flake or pellet yield, and sorting/washing rejection. The pilot data indicate that Lithuania had higher PET quality (98.2% PET purity, 80% clear PET, 1.8% non-PET impurities, IV = 0.74 dL/g, and 84.5% washed PET yield) than the Polish regional average (94.3% PET purity, 72.7% clear PET, 5.7% non-PET impurities, IV = 0.721 dL/g, and 80.3% washed PET yield). At R = 0.50, the pilot-derived PET HQR is approximately 37.8% for Lithuania and 31.6% for the Polish regional average. The results indicate that the same nominal return rate can lead to substantially different high-quality recovery outcomes because PET is constrained by stream purity, colour, contamination, and processing yield; aluminium by alloy and remelting control; and reusable glass by inspection, breakage, and refill compatibility. The proposed framework can support structured DRS operator reporting by identifying the material-quality and yield variables that should be measured alongside mass collection; however, operator-level validation is required before the model can be used as a predictive performance tool. Full article

Welding technology, extensively utilized in modern industry, poses significant health risks due to metal dust exposure, which can lead to respiratory discomfort, neurological issues, and an increased risk of lung cancer and pneumoconiosis. Enhancing ventilation within factory buildings has proven to be an economical approach to mitigating these risks. This study employs computational fluid dynamics (CFD) to model the airflow and dust transport within a large welding workshop measuring 300 m in length, 28 m in width, and 21 m in height. The impact of the exhaust-to-supply air ratio (ESR) and the height of the side exhaust port (SEP) on dust removal efficiency is investigated. Comparative analysis of transport dynamics between low-density aluminum alloy welding fume and high-density carbon steel welding fume reveals optimal dust exhaust designs. The study identifies two peaks in workshop air velocity at 0–2 m and 8–12 m above the ground, with the top exhaust port (TEP) outperforming the SEP in dust removal. An increased ESR accelerates the upward migration of welding fume, reducing lateral dispersion. An improperly set SEP height can lead to airflow short-circuiting or excessive lateral dispersion, hindering effective dust removal. Optimal SEP height for aluminum alloy and carbon steel dust are determined to be 5 m and 6 m, respectively. Full article

The development of titanium-based surface alloys and coatings that combine extreme hardness with sufficient toughness remains a major challenge for components operating under severe friction and wear conditions. In this work, titanium–boride composite coatings were synthesized on commercially pure titanium by scanning electron beam surface alloying of preplaced boron. The influence of beam power (900, 1200, and 1500 W) on phase formation, microstructural evolution, and mechanical performance was systematically investigated. At 900 W, insufficient melting resulted in chemically and structurally heterogeneous coatings containing unreacted boron. Increasing the beam power to 1200 W promoted the formation of TiB and TiB₂ phases, leading to a maximum microhardness of approximately 5500 HV_0.2. At 1500 W, complete boron incorporation produced a graded architecture consisting of a Ti/TiB surface layer and a TiB₂-rich sublayer. This hierarchical microstructure exhibited a favorable combination of high hardness and the lowest coefficient of friction (0.21), representing a reduction of more than 50% compared with the untreated titanium substrate. These findings establish a clear relationship between electron beam processing conditions, microstructural development, and mechanical performance, demonstrating that scanning electron beam surface alloying is an effective strategy for tailoring high-performance Ti–B composite surfaces. The developed coatings show strong potential for aerospace and other advanced engineering applications requiring lightweight materials with high hardness and low friction. Full article

5052 aluminum alloy has been widely used in aerospace, shipbuilding, automotive, and electronic industries due to its low density, high specific strength, and excellent corrosion resistance. Understanding its laser-induced damage behavior under combined continuous-wave (CW) and nanosecond (ns) pulse laser irradiation is essential for optimizing combined laser processing. In this study, the damage behaviors induced by individual CW laser, individual ns pulse laser, and combined pulse laser were systematically investigated using high-speed imaging, infrared thermography, and three-dimensional surface characterization. The results show that the combined pulse laser significantly enhances both damage depth and material removal efficiency compared with single laser irradiation. Although the peak surface temperature remains nearly unchanged under different processing conditions, the crater morphology and penetration depth vary substantially. High-speed imaging reveals that plasma evolution and molten metal ejection dominate the material removal process. Variations in processing parameters significantly modify molten pool dynamics and plasma behavior. In particular, enhanced plasma shielding or excessive energy dissipation reduces the effective laser energy coupling, leading to decreased material removal efficiency. The synergistic interaction among molten pool evolution, plasma expansion, and molten metal ejection governs the final damage morphology. This study provides new insights into the dynamic interaction mechanisms between combined pulse laser and aluminum alloys, offering guidance for parameter optimization in high-precision laser micromachining. Full article

Wittichenite Cu₃BiS₃ is a promising thermoelectric material with intrinsically low thermal conductivity owing to its complex crystal structure and strong lattice anharmonicity; however, its thermoelectric performance is limited by low carrier concentration and insufficient electrical conductivity. In this study, Cu₃Bi_1−xSn_xS₃ (x = 0.02–0.06) compositions were designed by substituting Sn⁴⁺ for Bi³⁺ sites, and dense single-phase bulk specimens were prepared using mechanical alloying followed by hot pressing. The effects of Sn doping on charge transport and thermoelectric properties were then systematically examined. Structural analysis confirmed that Sn was successfully incorporated into the Cu₃BiS₃ lattice without secondary phase formation, accompanied by anisotropic lattice contraction associated with the difference in ionic radii between Sn⁴⁺ and Bi³⁺. With increasing Sn content, the carrier concentration increased from approximately 10¹⁶ cm⁻³ to the 10¹⁷ cm⁻³ level, whereas the Hall mobility remained nearly unchanged, resulting in a substantial enhancement in electrical conductivity. Although the Seebeck coefficient decreased with increasing carrier concentration, the reduction was moderate, leading to an improved power factor of 0.10 mW·m⁻¹·K⁻² at 673 K. The thermal conductivity remained low, approximately 0.30–0.40 W·m⁻¹·K⁻¹, across the entire composition range, and the electronic contribution was less than 1%, indicating that heat transport was predominantly governed by the lattice contribution. These results demonstrate that Sn doping effectively improves the electrical transport properties while preserving the intrinsically low lattice thermal conductivity of Cu₃BiS₃. Consequently, a maximum ZT of 0.18 was achieved at 673 K, corresponding to a 64% improvement compared with the undoped specimen. Therefore, this study suggests that carrier concentration control via aliovalent doping is an effective strategy for enhancing the thermoelectric performance of wittichenite. Full article

This study investigates the atmospheric corrosion behavior of high-lead bronze alloys within a simulated aggressive environment characterized by high humidity, acidity, chlorides, oxygen, and CO₂. The evolution of surface morphology and corrosion products was systematically monitored using colorimetric analysis and micro-Raman spectroscopy. Results indicate that the initial patina primarily comprised cuprite (Cu₂O) and cassiterite (SnO₂), which are predominantly benign phases. During the early corrosion stage, lead oxidation and carbonation prevailed, generating abundant bright-white cerussite. Subsequently, as copper-driven corrosion became dominant, these white deposits diminished and were progressively replaced by characteristic green “bronze disease”, identified as atacamite (Cu₂(OH)₃Cl). The findings reveal that preferential lead corrosion is likely to induce localized pitting, thereby accelerating degradation of the copper substrate. Consequently, higher lead content may reduce the overall corrosion resistance of bronze artifacts under these specific conditions. These results offer experimental insights into atmospheric corrosion mechanisms and inform the development of evidence-based conservation strategies for bronze cultural heritage. Full article

The new Euro 7 standard will be the first legislation to limit the emissions produced by an automotive brake system. This has caused brake manufacturers to seek radical solutions to reduce the emissions generated from conventional grey cast iron (GCI) friction brakes. The regenerative braking system of electric vehicles (EVs) will require the friction brakes to be used less frequently than for an internal combustion engine vehicle. This may lead to a build-up of corrosion products on the friction surfaces that may not only affect the performance and service life of the GCI friction brake but also increase wear particle emissions when braking. Plasma electrolytic oxidation (PEO) ceramic-coated aluminium alloy rotors could be an alternative solution to reduce the effects of corrosion, produce lower brake emissions and also improve the energy efficiency of the EV by reducing its unsprung mass. To understand the interrelation between brake rotor corrosion and particulate emissions, this study concentrates on quantifying wear particles from a PEO-coated Al6082 brake rotor, both before and after exposure to salt fog corrosion. The results are compared to those for a standard uncoated GCI rotor and for an aluminium metal matrix composite (MMC) rotor subject to the same braking and corrosion test cycles. It was found that the PEO brake rotor produced a higher steady-state coefficient of friction in both the uncorroded and corroded conditions than either the GCI or MMC rotor, but emitted fewer wear particles in the uncorroded state, apart from at the highest brake line pressure. In the corroded state, the PEO rotor produced far lower emissions than either the corroded GCI or MMC rotors across all brake line pressures. Full article

The mechanical behavior of S135 and V150 (Mo-V-Nb microalloyed) drill pipe steels was systematically investigated at room temperature (RT) and elevated temperatures (100–300 °C), alongside the microstructural evolution after long-term thermal exposure at 310 °C (200–500 h). V150 steel exhibits a superior RT yield strength (1099 vs. 1012 MPa) relative to S135, attributed to grain refinement and precipitation strengthening from nanoscale MC precipitates. However, at 200–300 °C, S135 steel displays strength recovery due to dynamic strain aging (DSA) facilitated by the formation of Cottrell atmospheres. Conversely, in V150 steel, V and Nb pin free interstitial atoms, suppressing Cottrell atmosphere formation and DSA. Consequently, V150 cannot gain DSA-induced strengthening, resulting in a steeper yield strength decline (a 17.3% drop at 300 °C versus 11.5% for S135). Long-term thermal exposure further reveals divergent microstructural evolution: S135 steel achieves synchronous improvements in strength and ductility via the transformation of coarse M₃C into stable alloy carbides and the precipitation of nanoscale Mo-enriched carbides. In contrast, V150 steel undergoes Ostwald ripening and coherency loss of high-volume-fraction nano-MC precipitates, weakening dislocation pinning and accelerating dislocation annihilation, ultimately leading to the simultaneous degradation of strength and ductility. This study elucidates that while Mo-V-Nb microalloying enhances RT strength, it compromises high-temperature mechanical stability. Full article

The metastable β-phase Ti21S titanium alloy, characterised by its low Young’s modulus, oxidation resistance, creep strength, and high biocompatibility, has potential applications in aeronautical and biomedical fields. Despite these advantages, its adoption in additive manufacturing (AM) processes, particularly powder bed fusion with electron beam (PBF-EB), remains limited. A critical aspect of PBF-EB is the sintering phenomenon during preheating, which influences powder behaviour, thermal dissipation, and part quality. Insufficient sintering leads to poor energy dissipation and charge accumulation, while excessive sintering compromises powder reusability. This study investigates the sintering conditions required to optimise the PBF-EB preheating step for Ti21S. Thermogravimetric (TG) apparatus was employed as a controlled thermal treatment system to conduct a preliminary screening of the influence of temperature on powder sintering over a range of 400 °C to 700 °C. Parallel experiments were conducted using a PBF-EB machine to evaluate sintering behaviour. Scanning electron microscopy (SEM) was used to analyse the degree of sintering, while powder reusability was assessed by comparing the morphology and flowability of virgin and reused powders. The results show that conventional thermal treatment and PBF-EB preheating produce different sintering responses, likely because of the localised and rapid energy deposition associated with electron-beam heating. Nevertheless, controlled thermal treatment may provide a preliminary screening method for identifying temperature ranges for subsequent PBF-EB optimisation. Full article

Predicting the fatigue lives of high-performance alloys, specifically aluminum 7075-T6 and Inconel 718, is essential for ensuring structural integrity in applications such as aerospace and energy. While Poisson’s ratio is typically treated as a constant within fracture mechanics and finite element analysis, it has been found to vary significantly with increased temperatures and substantial amounts of plastic deformation. Variations in Poisson’s ratio can, therefore, have a significant impact on local stress fields around cracks and the behavior at crack tips. This study introduces a novel approach by systematically isolating the effects of varying Poisson’s ratios on fatigue life cycles, stress distributions, and fatigue crack growth using finite element analysis with the robust ANSYS SMART crack growth feature. The results indicate a stark difference in the effects of Poisson’s ratio on the fatigue life of aluminum 7075-T6 compared to Inconel 718. A strong negative correlation exists between Poisson’s ratio and fatigue life cycle numbers for aluminum 7075-T6, whereas a more linear trend is observed for all fatigue life cycle numbers of Inconel 718. The underlying reasons for these trends lie in the differing sensitivities of elastic, shear, and bulk moduli between the two alloys. Overall, a higher Poisson’s ratio intensifies the maximum principal stress for both alloys. Additionally, an increase in Poisson’s ratio leads to a decrease in von Mises stress for both metals. Furthermore, these numerical results demonstrate that an increase in Poisson’s ratio corresponds to a decrease in the cyclic plastic zone size at the crack tip for both alloys, indicating enhanced hydrostatic constraint and reduced shear deformation. The findings presented herein underscore the necessity of eliminating the use of static values for Poisson’s ratio when evaluating the structural performance of high-performance alloys under extreme operational environments. Additionally, this research highlights several key areas where existing modeling approaches are lacking and establishes a framework for developing improved constitutive models for fatigue life prediction. Full article

Copper and its alloys are indispensable for electronics, communications, new energy systems, and aerospace engineering due to their exceptional electrical conductivity and mechanical properties. However, the thin cuprous oxide (Cu₂O) layer that naturally forms on copper and its alloys is prone to failure under elevated temperatures and high humidity, particularly in chloride-rich environments, leading to accelerated localized corrosion. While conventional chromate-based passivation has long been the industrial standard for preventing corrosion, its use has been increasingly restricted by global regulations (such as RoHS and REACH) due to its severe toxicity and health risks. To address the conflict between environmental compliance and protective performance, this review systematically evaluates recent advances in environmentally friendly, chromium-free anti-corrosion coatings in the present review. These alternative coatings are critically analyzed and categorized into four mechanistic groups: (i) inorganic conversion coatings (including molybdate, tungstate, rare earth, and phosphate systems); (ii) organic films formed via chemical or physical adsorption (such as organic inhibitors, thiol-based monolayers, and organosilane self-assembled films); (iii) conversion coatings engineered through covalent bonding, coordination chemistry, and microstructural tailoring; and (iv) multifunctional coatings that integrate self-healing capability with high electrical conductivity. Beyond providing a technical summary, this review explored how the swift progression of electronic information technology, new energy infrastructure, and robotics has imposed more exacting, multifunctional demands on copper components. This review provides a strategic roadmap for future research and prioritizes the creation of protection strategies that operate robustly in multi-physics coupling environments—integrating high conductivity, autonomous self-healing, and long-term chemical stability to ensure the reliability of next-generation infrastructure. Full article

Sn-3Ag-0.5Cu-xBi alloys (SAC305-xBi) represent promising lead-free alternatives for low-temperature soldering. Low Bi concentrations can strengthen SAC-based solders through solid-solution strengthening, refining β–Sn grains and transforming needle-like Ag₃Sn phases into equiaxed morphologies. However, excessive Bi alloying may induce precipitation of brittle Bi particles, cause microstructural instability and interfacial degradation, thereby weakening the solder joint performance. As such, the concentration of Bi in the SAC305 alloys should be carefully controlled. In this work, the microstructure and corrosion behavior of Sn-3Ag-0.5Cu-xBi solder alloys (SAC305-xBi, where x = 0, 1, 2 and 4 wt. %) were investigated. Attention has been paid to the influence of low Bi concentration on the microstructure, morphology, and chemical composition of the phases present in the solder alloys before and after corrosion exposure. The alloys were prepared by induction melting of Sn, Ag, Cu and Bi lumps under Ar gas. The microstructure of the SAC305 and SAC305-1Bi alloys represented a hypoeutectic microstructure with dendritic (Sn) grains and the ternary eutectic, consisting of (Sn), Cu₆Sn₅ and Ag₃Sn, located in inter-dendritic regions. In the SAC305-2Bi and SAC305-4Bi alloys, a segregation of (Bi) particles was observed in addition to dendritic (Sn) and ternary eutectic. The (Bi) particles were located at the (Sn)Ag₃Sn interface in the inter-dendritic spaces of the (Sn) solid solution. The corrosion resistance of the as-cast alloys was studied in aqueous NaCl electrolyte (3.5 wt. %) using electrochemical methods. Open circuit potentials of the alloys were found to increase with increasing concentration of Bi. The highest corrosion current was found for the SAC305-1Bi alloy. It was observed that micro-galvanic cells at the Sn-Ag₃Sn interface were the initiating factors of corrosion in the SAC305-1Bi alloy. The corrosion activity of the SAC305-1Bi alloy is related to the high density of fine Ag₃Sn particles. The higher fraction of Ag₃Sn particles provided a dense network of local galvanic interaction sites, leading to the acceleration of the corrosion rate. The presence of discrete Bi precipitates in the SAC305-2Bi and SAC305-4Bi alloys, on the other hand, partially reduced the risk of galvanic corrosion. Since Bi has a higher standard electrode potential compared to Sn, the Bi/Ag₃Sn and Bi/Cu₆Sn₅ couples were less prone to corrosion. The corrosion mechanism of the SAC305-xBi alloys is discussed, and results are compared to previously studied SAC-Bi alloys. Full article